text readme refer to a broken link (#2840)
text readme refer to a broken link (#2840)

* Update specs.rst

* text readme refer to a broken link

the link should point to the master branch

MienDev/IdentityServer4,MienDev/IdentityServer4,IdentityServer/IdentityServer4,MienDev/IdentityServer4,IdentityServer/IdentityServer4,IdentityServer/IdentityServer4,IdentityServer/IdentityServer4,MienDev/IdentityServer4